• Resources Recycling
• /
• v.24 no.6
• /
• pp.45-53
• /
• 2015

There are few studies on the effects of different sources of PVC scraps generated after the end-of-life PVC products and these scraps are used to prepare PVC products of low quality. In this paper, rigid PVC scraps from different sources such as clothes, pipes, and others were investigated to incorporate into virgin PVC compounds as a part of efforts to recycle various PVC scraps effectively. It was found that the tensile strength and impact strength of the PVC compounds generally decreased with increasing the content of PVC scraps. The impact properties of scrap were in order of CC > PC > RC, tensile strength were PC > CC > RC and Vicat softening temperature shows no specific tendency. CC scraps contents of 50 phr of virgin PVC resin showed 80 %, and PC scrap with 50 phr of virgin resin showed 50% of the mechanical properties with virgin PVC.

• Elastomers and Composites
• /
• v.34 no.1
• /
• pp.11-19
• /
• 1999

Rebound, storage and loss modulus, and tan ${\delta}$ were investigated on cured rubbers with various ratios of sulfur to accelerator and the volume fraction of carbon black in the cured rubbers. The rebound was increased as the sulfur to accelerator ratio and the volume fraction of carbon black decreased. The storage modulus decreased as the loading of carbon black and the strain increased regardless of the cure systems. The network structure formed by filler-filler interaction was destroyed above 6% strain regardless of the loading of carbon black, because constant storage modulus was shown at the higher strain than 3% for $40{\sim}50phr$ loading of carbon black and at the higher strain than 6% for 60 phr and above loading of carbon black. Little effect on loss modulus was found at the low loading of carbon black, but the peak of loss modulus was shown at 1% strain as the loading of carbon black was increased. Tan ${\delta}$ increased as the loading of carbon black and the strain were increased regardless of the cure system, and maximum tan ${\delta}$ was shown at 2% strain regardless of the loading of carbon black.

• Journal of the Korea Society of Computer and Information
• /
• v.19 no.5
• /
• pp.27-35
• /
• 2014

The characteristics of today's health care industry, based on the state of the art IT can be represented as a paradigm of human-oriented ubiquitous and accessible as possible by U-Health care. In addition, the healthcare industry is information and communication technologies (ICT) developments regarding the many advances and applications based on the research being carried out actively. Medical information system has been developed toward combining information systems of medical IT and it sets its sights on the fusion of developed IT and u-healthcare system. So changing distributed medical information systems into a safe PHR integrated system based on IaaS cloud computing is suggested in order to forge u-healthcare system with the times in this paper. Our experimental results show that our proposed system increased the data access time by about 24% and reduces the waiting time for processing service by about 4.3% over the web-based PHR.

• Polymer(Korea)
• /
• v.37 no.1
• /
• pp.47-51
• /
• 2013

In this work, the effect of alumina nanofibers on thermal conductivity and fracture toughness of alumina nanofibers and powder filled epoxy (EP) composites were investigated with varying alumina nanofiber content from 20 to 100 phr. Thermal conductivity was tested using a laser flash analysis (LFA). The fracture toughness of the composites were studied through the critical stress intensity factor ($K_{IC}$) measurement. The mophologies were observed by scanning electron microscopy (SEM). From the results, it was found that the thermal conductivity was enhanced with increasing alumina nanofiber content, which played a key factor to determine the thermal conductivity. The $K_{IC}$ value was increased with increasing alumina nanofiber content, whereas the value decreased above 40 phr alumina nanofiber content. This was probably considered that the alumina nanofiber entangled each other in EP due to an excess of alumina nanofibers.

• Polymer(Korea)
• /
• v.28 no.5
• /
• pp.412-425
• /
• 2004

The influence of expandable graphite (EG) on flame retardancy and foaming properties of the NBR/GTR foams was studied. The foaming properties were similar to those of NBR/GTR foams without EG when the EG contents were 10$\~$30 phr. The LOI values were increased with the EG content. For cone-calorimeter test, the data showed the trend similar to that from experiment. When the composition ratios of the compounds of NBR/GTR were 100$\~$0/80$\~$20 (w/w), and the EG contents were 10$\~$30 phr, we obtained high flame retardancy foams with low heat release rate (HRR), total heat release (THR), effective heat of combustion (EHC) and carbon monoxide yield (COY). The smoke density is similar to CO yield values obtained by the cone-calorimeter test. TGA analysis also showed the results approximately similar to those from the LOI and cone-calorimeter experiments.

• Polymer(Korea)
• /
• v.35 no.4
• /
• pp.342-349
• /
• 2011

The effect of the amount of vinyltriethoxysilane (VTEOS) in precipitated silica filled silicone rubbers was extensively investigated in terms of the change of mechanical properties, heat resistance, oil resistance, compression set, resilience, and curing characteristics. As the content of VTEOS increased from 0 to 2.0 phr, the hardness of the silicone rubber increased, however, tensile strength, elongation at break, and tear strength decreased. From heat resistance test, the change of mechanical properties was pronounced for silicone rubber treated with more VTOES. The best heat resistance was achieved at 2.0 phr VTOES. In addition, oil resistance was proportionally improved with VTEOS content. From oil resistance test. it was found that the decrease in hardness and maximum elongation was reduced for VTEOS-added systems. Finally, resilience, compression set, degree of cure and crosslink density were significantly enhanced with the amount of VTEOS.

• Polymer(Korea)
• /
• v.37 no.6
• /
• pp.764-769
• /
• 2013

Starch was grafted by poly(methyl methacrylate) through the emulsion polymerization method. Modified starch/(acrylonitrile-butadiene rubber) (NBR) compounds were prepared by a latex blend method. The morphology, thermal properties and mechanical properties of the modified starch/carbon black/NBR composites were investigated with the change of starch concentration. The mechanical properties of the composites were improved by the addition of modified starch. But, when the concentration of modified starch was higher than 40 phr, the mechanical properties were deteriorated due to the poor dispersion of modified starch. At the same ratio of starch to carbon black, the composite showed a synergistic reinforcing effect by the good dispersion and high cross-linking density. In addition, the tensile strength, storage modulus, hardness, swelling and other properties were the best.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.37 no.12
• /
• pp.1465-1471
• /
• 2013

The electrical and mechanical properties of room temperature vulcanized (RTV) silicone rubber composites are investigated as functions of multi-walled carbon nanotube (CNT), carbon black (CB), and thinner content. The thinner is used to improve the CNT and CB dispersion in the matrix. The electrical and mechanical properties of the composite with CNT are improved when compared to the composite with CB at the same content. As the thinner content is 80 phr, the electric resistance of the composite decreases significantly with the CNT content and shows contact point saturation of CNT at 2.5 phr. As the thinner content increases, the dispersion of conductive particles improves; however, the critical CB content increases because of the reduction in the CB weight ratio. It is believed that an electrode that needs good flexibility and excellent electrical properties can be manufactured when the amount of CNT and CB are increased with the thinner content.

• Applied Chemistry for Engineering
• /
• v.27 no.2
• /
• pp.179-184
• /
• 2016

In this work, the influence of milled carbon fiber direction on mechanical properties of milled carbon fibers/carbon blacks/natural rubber compounds was investigated. The compounds were prepared by adding the 6 phr milled carbon fibers (MCFs) and 40 phr carbon blacks (CBs) into the natural rubber. The MCFs were aligned in a parallel and orthogonal direction in the compounds using two-roll-mill machine. Mechanical properties of compounds were studied by tensile characteristics and tearing strength. As a result, the compounds showed higher tensile strength, 100%~300% modulus, and tearing strength than those of using any other compounds due to the aligning MCFs in parallel. Mechanical properties of the compounds reinforced with non-aligned MCFs were inferior to those of others. Consequently, the parallel aligned MCFs in the compounds led to an increase of tensile properties and improvement of tearing strength, resulted from MCFs with the high elastic modulus.

• Elastomers and Composites
• /
• v.38 no.1
• /
• pp.72-80
• /
• 2003

Phosphoric ester compound was employed as thermal resistant and flame retardant for chlorinated polyethylene(CPE) rubber material which is used to prepare automotive oil cooler hose. Cure characteristics, physical properties, thermal resistance, and flame retardation of CPE rubber compounds were investigated. CPE rubber which has excellent properties such as cold resistance and chemical corrosion resistance, and is inexpensive in price than existing ethyleneacrylate rubber(EAR) was used to prepare a rubber compound useful for hose. A non-halogen flame retarding agent N,N'-bis- (diphenylphosphoro) diaminohexane(BDPDH), which is condensed phosphoric ester, was synthesized and it was mixed to CPE rubber material with the range of $0{\sim}30 phr$. From the test results, rheological properties, heat resistance, and flame retardance of CPE rubber compounds were found out to be much increased. The optimum content of BDPDH to rubber which gives maximum effect on thermal resistance and flame retardation, within the range of tolerable specification for rubber materials, was determined to be 20 phr.